Spring Data JPA: Creating Specification Subquery from different tables - spring

Question

I am trying to build a specifications to predicate subquery for the below query.
Select u.* from User u where u.login in (select ur.role_id from userRoles ur where ur.role_Id = roleId).
till now this is the part I have built
public static Specification<User> userRoleId(String roleId) {
return new Specification<User>() {
#Override
public Predicate toPredicate(Root<User> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
//return builder.equal(root.<LocalDate> get("scheduledDisbursementDate"), scheduledDisbursementDate);
Subquery<UserRole> subquery = query.subquery(UserRole.class);
Root<UserRole> subqueryRoot = subquery.from(UserRole.class);
subquery.select(subqueryRoot);
Predicate roleIdList = builder.equal(subqueryRoot.get("roleId"), roleId);
subquery.select(subqueryRoot).where(roleIdList);
return builder.exists(subquery);
}
};
}
Can you please help me out to link the subquery with main query.
Note: There are no joins defined in the Entity classes. evrything should be done through subquerys only

Answer 1

Found Answer
first predicate will join UserRole userId column with and User table login column.
Second predicate will filter the condition based on roleId.
public static Specification<User> userRoleId(String roleId) {
return new Specification<User>() {
#Override
public Predicate toPredicate(Root<User> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
Subquery<UserRole> subquery = query.subquery(UserRole.class);
Root<UserRole> subqueryRoot = subquery.from(UserRole.class);
subquery.select(subqueryRoot);
Predicate userIdPredicate = builder.equal(subqueryRoot.get("userId"), root.<String> get("login"));
Predicate rolePredicate = builder.equal(subqueryRoot.get("roleId"), roleId);
subquery.select(subqueryRoot).where(userIdPredicate, rolePredicate);
return builder.exists(subquery);
}
};
}